1. Field of the Invention
The present invention relates to an ink jet recording apparatus that performs recording by discharging ink to a recording medium such as a recording sheet, and more specifically, it relates to an ink jet recording apparatus that reduces adhesion of ink mist to the recording medium, the ink mist being generated in the recording.
2. Description of the Related Art
In an ink jet recording apparatus, when ink is discharged to a recording medium to record an image, in addition to normal ink drops, minute ink drops called satellites are generated. In addition, the discharged normal ink drops bounce off the recording medium to generate other minute ink drops. These minute ink drops become an ink mist and are scattered and suspended in the recording apparatus. The mist contaminates components of the apparatus. If the mist adheres to a part on which a recording medium is conveyed, such as a paper guide, the conveyed recording medium is smudged. If the mist adheres to an optical sensor, defective detection is caused. If the mist adheres to a guide member for a carriage of a serial recording apparatus, increased resistance to the carriage causes defective operation.
Hitherto, in order to prevent the ink mist from being generated or adhering to specific parts of the apparatus, various constitutions have been proposed. For example, by modifying a recording head, which discharges ink, the satellites are prevented from being generated, and therefore the ink mist is prevented from being generated. Alternatively, by introducing air into the space between the recording head and the recording medium with a fan, the ink mist is prevented from adhering to the recording medium (see, for example, Japanese Patent Laid-Open No. 06-166173).
A so-called full line type ink jet printer uses a recording head in which many ink-discharging nozzles are arranged in the width direction of the conveyed recording medium. The full line type ink jet printer has various advantages such as high-speed recording. The full line type ink jet printer generally uses an electrostatic conveyer belt as a recording-medium conveying mechanism. The conveyer belt holds a recording medium with electrostatic attracting force. More specifically, potential difference is generated between an electrode plate and a ground plate embedded in the conveyer belt, thereby generating an electric field. The electric field dielectrically polarizes the recording medium. In this way, the recording medium and the conveyer belt have charges of opposite polarity. Due to the electrostatic force, the recording medium is attracted to the conveyer belt. By using such a method for conveying, the recording medium is fastened to the conveyer belt, and defects in the recorded image and jamming are reduced (see, for example, Japanese Patent Laid-Open No. 2000-095374, corresponding to U.S. Pat. No. 6,419,411).
In a recording apparatus using the above electrostatic conveyer belt, if a recording head preventing the ink mist from being generated is used, or if a mechanism, such as a fan, preventing the ink mist from adhering to specific parts is used, the problems concerning ink mist adhesion can be solved to some extent. However, due to the electric field generated on the conveyer belt, the recording medium itself attracts the ink mist. Even if a recording head preventing the ink mist from being generated and a mechanism preventing the ink mist from adhering to specific parts are used, a little ink mist is still generated and adheres to the recording medium, thereby deteriorating recording quality. If neither a recording head preventing the ink mist from being generated nor a mechanism preventing the ink mist from adhering to specific parts is used, the problem of the ink mist adhering to the recording medium due to the electric field becomes noticeable.